using System.IO;

using Org.BouncyCastle.Utilities.IO;

namespace Org.BouncyCastle.Asn1
{
	public class BerGenerator
		: Asn1Generator
	{
		private bool      _tagged = false;
		private bool      _isExplicit;
		private int          _tagNo;

		protected BerGenerator(
			Stream outStream)
			: base(outStream)
		{
		}

		public BerGenerator(
			Stream outStream,
			int tagNo,
			bool isExplicit)
			: base(outStream)
		{
			_tagged = true;
			_isExplicit = isExplicit;
			_tagNo = tagNo;
		}

		public override void AddObject(
			Asn1Encodable obj)
		{
			new BerOutputStream(Out).WriteObject(obj);
		}

		public override Stream GetRawOutputStream()
		{
			return Out;
		}

		public override void Close()
		{
			WriteBerEnd();
		}

		private void WriteHdr(
			int tag)
		{
			Out.WriteByte((byte) tag);
			Out.WriteByte(0x80);
		}

		protected void WriteBerHeader(
			int tag)
		{
			if (_tagged)
			{
				int tagNum = _tagNo | Asn1Tags.Tagged;

				if (_isExplicit)
				{
					WriteHdr(tagNum | Asn1Tags.Constructed);
					WriteHdr(tag);
				}
				else
				{
					if ((tag & Asn1Tags.Constructed) != 0)
					{
						WriteHdr(tagNum | Asn1Tags.Constructed);
					}
					else
					{
						WriteHdr(tagNum);
					}
				}
			}
			else
			{
				WriteHdr(tag);
			}
		}

		protected void WriteBerBody(
			Stream contentStream)
		{
			Streams.PipeAll(contentStream, Out);
		}

		protected void WriteBerEnd()
		{
			Out.WriteByte(0x00);
			Out.WriteByte(0x00);

			if (_tagged && _isExplicit)  // write extra end for tag header
			{
				Out.WriteByte(0x00);
				Out.WriteByte(0x00);
			}
		}
	}
}
